A COMPARISON OF THE EFFECT OF DROUGHT AND LOW ROOT TEMPERATURES ON LEAF ELONGATION AND PHOTOSYNTHESIS IN MAIZE

Although factors in the root medium will primarily affect root growth and root activity, due to the dependence of the shoots on various activities of the roots, these factors may also affect the shoot activities.
Since the growth rate of a plant depends mainly on the rate of leaf area development and on the rate of dry matter production per unit leaf area, these processes are to be considered as the key-processes in the reaction of the plant upon its environment.
In long term experiments they are interrelated upon each other since they are in combination responsible for the value of the leaf area ratio (LAR cm² g^-1).

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The short term effects of the environment on LAR are not easily to be detected.
In all cases LAR is determined by the average condition in which the plants are grown.
Both a dry soil and a cold soil tend to lower LAR values.

This paper mainly dealt with short term effects as encountered during short drought periods and changing soil temperatures.
Both leaf elongation and photosynthesis are continuously recorded, whereas changes in root temperature and light intensity are regularly induced during the normal light-dark cycles of climate rooms and glass house.
It appeared that the rate of leaf elongation is much more sensitive to drought and low root temperatures than the rate of photosynthesis.
Hence the reduction in dry matter production is quantitatively more important in freely growing plants than in closed crops.

Symposium on Basic Problems of Protected Vegetable Production

R. Brouwer

https://doi.org/10.17660/ActaHortic.1974.39.13